Picture Frame Bracket to fit IKEA Ribba frames

We recently bought some Ikea picture frames and were having trouble mounting them on the wall. I came up with this design for two brackets which screw to the back of the deep frame enabling a piece of string, cord or wire to be stretched across between the brackets to facilitate mounting the picture.

Simple but effective I think. (A bit like me!!!)

this is the picture frame it fits
http://www.ikea.com/gb/en/catalog/products/70153160/

I modified the design after printing out the fir